This invention relates to ladder latch systems, specifically those used to secure telescoping ladders used in a marine environment.
In a marine environment, ladders are components that are essential in order for people to board and exit boats safely and easily. These ladders, once they have been used for either boarding or leaving the boat, need to be removed from the side of the boat once it is under way. This is necessary to prevent drag, or to prevent the ladder from catching on any objects. It is also necessary to prevent damage to the ladder itself while the boat is being docked. This necessity has led to the widespread use of telescoping ladders on most recreational and other marine craft. Adhered to the boat like other ladders, telescoping ladders, like their name implies, can be easily and safely retracted, just like a telescope, back on board the boat once the craft is under way or after they have served their purpose. When they are needed again, they are simply extended out over the side of the boat. In its retracted position, the ladder rests on the deck on top of a platform or slides underneath and rests under it.
A typical telescoping ladder has three to four steps, and in the retracted position these steps rest closely against each other but have nothing preventing them from being extended accidentally. An accidental extension like this could take place while the ship rolls during heavy seas, or while the ladder itself is being transported. Such an accidental extension could result in injury to a passenger or damage to the boat itself Therefore the need has arisen for some type of latch, or fastener, to secure the ladder""s steps while the ladder is retracted and not in use. And since the space on water-going vessels is limited, any telescoping ladders used on such vessels need to be compact and space efficient. And therefore, any fastener that might be a component of this type of ladder also needs to be small and compact. In addition, since this environment involves water, any fastener used here also needs to be sufficiently resistant to and unexposed to the corrosive effects of water. One such fastener already developed is one used to secure a collapsible fire ladder in U.S. Pat. No. 5,022,491 to Gill, Jun. 11, 1991. But this is for a collapsible ladder used as an escape ladder in case of an emergency, and is too large and bulky to be used on a telescoping ladder in a marine environment. Also, this fastener is exposed to the elements, leaving it vulnerable to rust and corrosion.
Another invention utilizing the concept of a retractable or telescoping ladder and latch, is presented in U.S. Pat. No. 5,743,355 to McDonnell et al, Jul. 31, 1996. This device has all the conveniences of a telescoping ladder, such as easy storage and compactness. However, the latch it utilizes is an overly complex device that requires manual manipulation initially to be set, and then further manipulation through levers to be locked into place. The levers themselves extend from the uppermost rung of the ladder, and as a result could interfere with securing a safe grip on that rung.
Despite their latching system""s shortcomings, these two retractable ladder systems are better than most telescoping ladder systems which do not have latches or any other means to secure them when they are in a retracted position.
Some important objects of the invention presented here are to provide a latch system for a telescoping ladder that is lightweight, easy to use, strong, inconspicuous, and space efficient. An additional object is to provide a latch system that is resistant to the effects of the elements such as rust and corrosion.
Most of the few ladder latch systems that exist are either too cumbersome or too complex to be used in an easy, reliable, effective, and safe manner. The use of telescoping ladders brings with it the danger of accidental extension, which could cause injury to people or damage to property. Consequently, the use of these ladders demands the accompanying use of a latch system to safely secure the ladder when it isn""t being used. The ladder latch system presented here provides a strong, lightweight, easy-to-use system for safely and effectively securing telescoping ladders when they are in a retracted position.
Accordingly, several objects and advantages of this invention are:
1. The ladder latch system requires little space whether in use or not. It does this by being positioned along the ladder-mounting bracket and by being aligned with the innermost leg of the telescoping ladder. To secure the telescoping legs, the legs are pushed in the direction of and over the latch. The latch, now inside the ladder legs, secures the telescoping legs by hooking onto a catch that is a part of the innermost ladder leg. In this way the latch secures the ladder legs while remaining out of sight. And it does this while requiring only a minimal amount of external space.
2. The ladder latch system is easy to operate. To engage the latch, all that needs to be done is to slide the ladder back into the retracted position. Whenever this happens, the latch automatically secures the ladder legs by catching on the catch inside the innermost ladder leg. To release the latch, a knob is pressed at the base of the ladder legs which in turn presses on a rod that pushes the latch away from the catch. This disengages the latch in a quick and uncomplicated manner.
3. The system is simple in design and durable. Its components consist of a spacer, a latch, some screws, some nuts, a knob, a spring, a rod, and a pin. The catch that the latch engages when the system is in use is the half circle portion of the end of the innermost ladder leg. This catch has no moving parts or complex levers. And since the innermost ladder leg is usually made of one molded, metal piece, the catch itself is made of metal and is therefore strong and highly durable. The release mechanism is also simple in design. It is comprised of a rod inside the innermost ladder leg that is attached to a knob utilizing a spring action to push the rod forward. The spring returns the entire release mechanism to its normal position after the knob has ceased being depressed. The knob containing the spring is anchored to the innermost ladder leg with a pin. Like the ladder latch mechanism that secures the ladder legs, it has no complex levers or moving parts that are delicate enough to break down easily or too difficult to repair.